Updated header interfaces and class to include an opening/closing header flag and tested and corrected equals() methods across all implementations of DataHeader

Modified files:
src/binary/ProtocolHeaderImpl.java
src/binary/ProtocolInputReader.java
src/dataTransfer/DataHeader.java
src/dataTransfer/DataHeaderImpl.java
src/xml/XMLInputReader.java
src/xml/XMLTagImpl.java
src/xml/binary/XMLInputStream.java